A conventional damper control apparatus controls a damping force of a damper interposed between a sprung member and an unsprung member of a vehicle. The damper control apparatus controls the damping force of the damper by focusing on an expansion/contraction displacement and an expansion/contraction speed of the damper, for example. This type of damper control apparatus suppresses rattling of the unsprung member by determining whether the damper is decelerating or accelerating, and increasing a control gain so that the damper generates a large damping force when the damper is decelerating. When the damper is accelerating, on the other hand, the damper control apparatus improves a road surface following performance of the unsprung member by reducing the control gain so that the damper generates a small damping force. As a result, passenger comfort in the vehicle is improved (see JP2007-210590A).
A different type of damper control apparatus controls the damping force of the damper by focusing on a frequency and an amplitude of an expansion/contraction acceleration of the damper, for example. This type of damper control apparatus improves the passenger comfort of the vehicle by determining a road surface condition, selecting an appropriate damping force map for the road surface condition, and controlling the damping force of the damper in accordance with the selected damping force map (see JP2002-144837A).